KANSAS CITY, Mo. (AP) – Two NFL Hall of Famers are among nine former Kansas City Chiefs players who have joined a lawsuit that contends the team hid the risks of permanent brain injuries from repeated concussions.

Cornerback Albert Lewis and defensive end Art Still were added Saturday to the lawsuit initially filed this month on behalf of five former Chiefs players. Also joining the suit are Dino Hackett, Todd McNair, Fred Jones, Tim Barnett, Walker Lee Ashley, Emile Harry and Chris Smith.

All 14 plaintiffs were on the team between 1987 and 1993, a period when there was no collective bargaining agreement in place in the NFL.  The amended lawsuit also adds claims that artificial-surface fields during part of that time contributed to concussions.